Electron transport in a sequentially doped naphthalene diimide polymer

Abstract

The effects of sequential n-doping on a high-electron-mobility naphthalene-diimide-based copolymer poly[(N,N′-bis(2-decyltetradecyl)-naphthalene-1,8:4,5-bis(dicarboximide)-2,6-diyl)-(selenophene-2,5-diyl)-(benzo[c][1,2,5]thiadiazole-4,7-diyl)-(selenophene-2,5-diyl)], PNBS, are reported. Grazing-incidence XRD measurements show that PNBS doped with 2,2′-bis(4-(dimethylamino)phenyl)-1,1′,3,3′-tetramethyl-2,2′,3,3′-tetrahydro-1H,1′H-2,2′-bibenzo[d]imidazole, (N-DMBI)₂, has increased order relative to both the pristine polymer and a film doped with ruthenium pentamethylcyclopentadienyl mesitylene dimer. Films of PNBS optimally doped with (N-DMBI)₂ show electrical conductivities approaching 2 mS cm⁻¹ in air. Temperature-dependent electrical measurements suggest that the polaronic charge carriers are highly localized, which is consistent with the moderate conductivity values obtained.